The Heidelberg Catechism: Lord's Day 37101. Question: But may we swear an oath by the Name of God in a godly manner?

Answer: Yes, when the government demands it of its subjects, or when necessity requires it, in order to maintain and promote fidelity and truth, to God's glory and for our neighbor’s good. Such oath-taking is based on God's Word[1] and was therefore rightly used by saints in the Old and the New Testament.[2]